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| United States Patent |
5,502,119
|
|
Hamilton
|
March 26, 1996
|
Stabilized polyester-polycarbonate compositions
Abstract
A polyester-polycarbonate composition comprising (A) at least one polyester
prepared by the reaction of at least one alkanediol with at least one
dicarboxylic acid or dialkyl ester thereof in the presence of a metallic
catalyst, (B) at least one polycarbonate, (C) at least one organosilicate,
the organosilicate being present in an amount effective to inhibit
ester-carbonate interchange in the composition, optionally, (D) an organic
or inorganic colorant, (E) an impact modifier, and (F) a stabilizer. A
method for stabilizing polyester-polycarbonate compositions against
ester-carbonate interchange is also provided.
| Inventors:
|
Hamilton; Douglas G. (Mt. Vernon, IN)
|
| Assignee:
|
General Electric Company (Pittsfield, MA)
|
| Appl. No.:
|
396353 |
| Filed:
|
February 28, 1995 |
| Current U.S. Class: |
525/439; 524/81; 524/261; 524/539; 525/437; 525/446; 525/461; 525/464; 528/272; 528/275; 528/279; 528/280; 528/281; 528/282; 528/283; 528/285; 528/308; 528/308.6 |
| Intern'l Class: |
C08F 020/00 |
| Field of Search: |
528/272,275,279,280,281,282,283,285,308,308.6
525/437,439,446,461,464
524/81,261,539
|
References Cited
U.S. Patent Documents
| 4401804 | Aug., 1983 | Wooten et al. | 528/272.
|
| 4532290 | Jul., 1985 | Jaquiss et al. | 524/417.
|
| 4794141 | Dec., 1988 | Paul et al. | 525/92.
|
| 5025066 | Jun., 1991 | DeRudder et al. | 525/66.
|
| Foreign Patent Documents |
| 65777 | Dec., 1982 | EP.
| |
| 230047A | Jul., 1987 | EP.
| |
| 279678A | Jun., 1990 | DE.
| |
| 58-187450A | Nov., 1983 | JP.
| |
| 61-203164A | Sep., 1986 | JP.
| |
| 62-158753A | Jul., 1987 | JP.
| |
| 1284549 | Nov., 1989 | JP.
| |
| 2112177A | Apr., 1990 | JP.
| |
Primary Examiner: Acquah; Samuel A.
Parent Case Text
This is a continuation of Ser. No. 07/984,766, filed on Dec. 3, 1992, now
abandoned.
Claims
What is claimed is:
1. A polyester-polycarbonate composition comprising (A) at least one
polyester prepared by the reaction of at least one alkanediol with at
least one dicarboxylic acid or dialkyl ester thereof in the presence of a
metallic catalyst, (B) at least one polycarbonate, and (C) at least one
organosilicate having the general formula
(R).sub.a (R.sup.1 O).sub.b Si
or
(R.sup.2).sub.c (R.sup.3 O).sub.d SiO- -(Si(R.sup.4).sub.e (OR.sup.5).sub.f
O).sub.h -(Si(R.sup.6).sub.j (R.sup.7).sub.k O).sub.l !.sub.n Si(R.sup.8
O).sub.p (R.sup.9).sub.q
or
##STR5##
wherein 0.ltoreq.a.ltoreq.3; 1.ltoreq.b.ltoreq.4; a+b=4;
0.ltoreq.c.ltoreq.3; c+d=3; 0.ltoreq.e.ltoreq.2; 0.ltoreq.f.ltoreq.2;
e+f=2; 0.ltoreq.h.ltoreq.20; 0.ltoreq.j.ltoreq.2; 0.ltoreq.k.ltoreq.2;
j+k=2; 0.ltoreq.l.ltoreq.20; 0.ltoreq.n.ltoreq.100; 0.ltoreq.p.ltoreq.3;
0.ltoreq.q.ltoreq.3; d+f+p>0; p+=3; R, R.sup.1, R.sup.2, R.sup.3, R.sup.4,
R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are each independently H,
an alkyl radical having 1-20 carbon atoms, an aryl radical having 6-20
carbon atoms, an alkylaryl radical having 1-20 carbon atoms, an alkenyl
radical having 1-20 carbon atoms, or halogenated derivatives of the
foregoing; wherein the organosilicate is present in an amount sufficient
to substantially inhibit ester-carbonate interchange in the composition.
2. A composition according to claim 1 wherein each R independently
represents an alkyl radical, an aryl radical, an aralkyl radical, or an
alkenyl radical.
3. A composition according to claim 1 wherein the organosilicate is
Si(OCH.sub.3).sub.4, Si(OCH.sub.2 CH.sub.3).sub.4, Si(OCH.sub.3).sub.2
(OCH.sub.2 CH.sub.3).sub.2, (CH.sub.3)Si(OCH.sub.2 CH.sub.3)(OPh).sub.2,
(CH.sub.3)Si(OCH.sub.2 CH.sub.3).sub.3, (CH.sub.3).sub.2 Si(OCH.sub.2
CH.sub.3).sub.2, (CH.sub.3).sub.3 Si(OCH.sub.2 CH.sub.3), Si(OCH.sub.2
CH.sub.3).sub.3 H, or Si(OPh).sub.4, poly(diethoxy)silicate, wherein Ph is
a phenyl radical.
4. A composition according to claim 1 wherein the organosilicate is
Si(OPh).sub.4, Si(OCH.sub.2 CH.sub.3).sub.4, or poly(diethoxy)silicate;
wherein Ph is phenyl.
5. A composition according to claim 1 wherein the amount of organosilicate
ranges from about 0.01 to about 10 parts by weight.
6. A composition according to claim 5 wherein the amount of organosilicate
ranges from about 0.01 to about 5 parts by weight.
7. A composition according to claim 6 wherein the amount of organosilicate
ranges from about 0.01 to about 1 part by weight.
8. A composition according to claim 1 wherein the polycarbonate is a
bisphenol A polycarbonate and the polyester is polybutylene terephthalate.
9. A composition according to claim 1 wherein the metallic catalyst is an
organic or inorganic compound selected from the group consisting of
organic or inorganic compounds of arsenic, cobalt, tin, antimony, zinc,
titanium, magnesium, calcium, manganese, gallium, sodium, and lithium.
10. A composition according to claim 9 wherein the metallic catalyst is a
titanium compound.
11. A composition according to claim 10 wherein the titanium compound is
tetraisopropyl titanate or tetra(2-ethylhexyl)titanate.
12. A composition according to claim 1 further comprising one or more of an
organic or inorganic colorant; an impact modifier; a stabilizer; or glass.
13. A polyester-polycarbonate composition comprising (A) at least one
polybutylene terephthalate prepared by the reaction of at least one
alkanediol with at least one dicarboxylic acid or dialkyl ester thereof in
the presence of a titanium compound catalyst; (B) at least one bisphenol A
polycarbonate, (C) at least one organosilicate having the formula
Si(OPh).sub.4 or Si(OCH.sub.2 CH.sub.3).sub.4, wherein Ph is phenyl, (D)
an inorganic or organic colorant, and (E) an impact modifier.
14. A composition according to claim 13 further comprising one or more of a
stabilizer or glass.
15. A polyester-polycarbonate composition consisting essentially of: (A) at
least one polyester prepared by the reaction of at least one alkanediol
with at least one dicarboxylic acid or dialkyl ester thereof in the
presence of a metallic catalyst, (B) at least one polycarbonate, and (C)
at least one organosilicate having the general formula
(R).sub.a (R.sup.1 O).sub.b Si
or
(R.sup.2).sub.c (R.sup.3 O).sub.d SiO- -(Si(R.sup.4).sub.e (OR.sup.5).sub.f
O).sub.h -(Si(R.sup.6).sub.j (R.sup.7).sub.k O).sub.l !.sub.n Si(R.sup.8
O).sub.p (R.sup.9).sub.q
or
##STR6##
wherein 0.ltoreq.a.ltoreq.3; 1.ltoreq.b.ltoreq.4; a+b=4;
0.ltoreq.c.ltoreq.3; c+d=3; 0.ltoreq.e.ltoreq.2; 0.ltoreq.f.ltoreq.2;
e+f=2; 0.ltoreq.h.ltoreq.20; 0.ltoreq.j.ltoreq.2; 0.ltoreq.k.ltoreq.2;
j+k=2; 0.ltoreq.l.ltoreq.20; 0.ltoreq.n.ltoreq.100; 0.ltoreq.p.ltoreq.3;
0.ltoreq.q.ltoreq.3; d+f+p>0; p+q=3; R, R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are each
independently H, an alkyl radical having 1-20 carbon atoms, an aryl
radical having 6-20 carbon atoms, an alkylaryl radical having 1-20 carbon
atoms, an alkenyl radical having 1-20 carbon atoms, or halogenated
derivatives of the foregoing; wherein the organosilicate is present in an
amount sufficient to substantially inhibit ester-carbonate interchange in
the composition.
16. A composition according to claim 15 further comprising one or more of
an organic or inorganic colorant, an impact modifier, a stabilizer, or
glass.
17. A method for inhibiting the ester-carbonate interchange in a
polyester-polycarbonate composition comprising (A) at least one polyester
prepared by the reaction of at least one alkanediol with at least one
dicarboxylic acid or dialkyl ester thereof in the presence of a metallic
catalyst, (B) at least one polycarbonate; wherein the method comprises
contacting the polyester-polycarbonate composition with an effective
amount of (C) at least one organosilicate having the general formula
(R).sub.a (R.sup.1 O).sub.b Si
or
(R.sup.2).sub.c (R.sup.3 O).sub.d SiO- -(Si(R.sup.4).sub.e (OR.sup.5).sub.f
O).sub.h -(Si(R.sup.6).sub.j (R.sup.7).sub.k O).sub.l !.sub.n Si(R.sup.8
O).sub.p (R.sup.9).sub.q
or
##STR7##
wherein 0.ltoreq.a.ltoreq.3; 1.ltoreq.b.ltoreq.4; a+b=4;
0.ltoreq.c.ltoreq.3; c+d=3; 0.ltoreq.e.ltoreq.2; 0.ltoreq.f.ltoreq.2;
e+f=2; 0.ltoreq.h.ltoreq.20; 0.ltoreq.j.ltoreq.2; 0.ltoreq.k.ltoreq.2;
j+k=2; 0.ltoreq.l.ltoreq.20; 0.ltoreq.n.ltoreq.100; 0.ltoreq.p.ltoreq.3;
0.ltoreq.q.ltoreq.3; d+f+p>0; p+q=3; R, R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are each
independently H, an alkyl radical having 1-20 carbon atoms, an aryl
radical having 6-20 carbon atoms, an alkylaryl radical having 1-20 carbon
atoms, an alkenyl radical having 1-20 carbon atoms, or halogenated
derivatives of the foregoing; wherein the organosilicate is present in an
amount sufficient to substantially inhibit ester-carbonate interchange in
the composition.
18. A method according to claim 17 further comprising the step of combining
the polyester-polycarbonate composition with one or more of an organic or
inorganic colorant, an impact modifier, a stabilizer, or glass.
19. The polyester-polycarbonate composition of claim 1, wherein f is either
1 or 2.
20. The polyester-polycarbonate composition of claim 19, wherein f is 2.
Description
BACKGROUND OF THE INVENTION
The present invention relates to polycarbonate-polyester compositions. More
particularly, the present invention relates to improved
polyester-polycarbonate compositions stabilized against ester-carbonate
interchange.
Polyester-polycarbonate compositions are widely used in industry. However,
a disadvantage of these compositions is their tendency to undergo
ester-carbonate interchange, wherein ester linkages in both the
polycarbonate and the polyester are believed to be broken and replaced by
alkylene carbonate and aryl carboxylate bonds. The result is degradation
of the physical properties of the polymers due to hybridization of the
molecular linkages therein. This in turn leads to variability in the final
fabricated article.
It is believed that the ester-carbonate interchange in
polyester-polycarbonate compositions is promoted by metallic catalyst
residues present in the polyester. These residues are left over from the
polymerization reaction forming the polyester, wherein certain metal
compounds are used as polymerization catalysts. It appears, however, that
these metal compounds also catalyze the transesterification reaction
between the polycarbonate and the polyester.
It would be desirable to provide a compound which deactivates the metallic
catalyst residues present in the polycarbonate/polyester compositions. The
resulting polyester-polycarbonate compositions would be improved in that
they would have a decreased tendency to undergo ester-carbonate
interchange and therefore would be stable against such interchange.
It is known in the art that certain phosphorous-containing inorganic
compounds are useful in deactivating metallic catalyst residues. Reference
is made, for example, to U.S. Pat. Nos. 4,532,290 (Jaquiss et al.) and
4,401,804 (Wooten et al.).
Copending, commonly assigned U.S. Patent Application Docket Number
8CV-5282, filed Jun. 2, 1992, to Douglas G. Hamilton (Serial Number not
yet assigned) discloses the use of silyl phosphates to deactive metallic
catalyst residues in polyester-polycarbonate compositions.
The present invention is based on the discovery that certain
organoorthosilicates compounds will effectively deactivate metallic
catalyst residues in a polycarbonate-polyester composition.
SUMMARY OF THE INVENTION
The present invention provides a polyester-polycarbonate composition
comprising (A) at least one polyester prepared by the reaction of at least
one alkanediol with at least one dicarboxylic acid or dialkyl ester
thereof in the presence of a metallic catalyst, (B) at least one
polycarbonate, the sum of the weight of (A) and (B) being 100 parts by
weight; and (C) at least one organosilicate having the general formula
(R).sub.a (R.sup.1 O).sub.b Si
or
(R.sup.2).sub.c (R.sup.3 O).sub.d SiO- -(Si(R.sup.4).sub.e (OR.sup.5).sub.f
O).sub.h -(Si(R.sup.6).sub.j (R.sup.7).sub.k O).sub.l !.sub.n Si(R.sup.8
O).sub.p (R.sup.9).sub.q
or
##STR1##
wherein 0.ltoreq.a.ltoreq.3; 1.ltoreq.b.ltoreq.4; a+b=4;
0.ltoreq.c.ltoreq.3; c+d=3; 0.ltoreq.e.ltoreq.2; 0.ltoreq.f.ltoreq.2;
e+f=2; 0.ltoreq.h.ltoreq.20; 0.ltoreq.j.ltoreq.2; 0.ltoreq.k.ltoreq.2;
j+k=2; 0.ltoreq.l.ltoreq.20; 0.ltoreq.n.ltoreq.100; 0.ltoreq.p.ltoreq.3;
0.ltoreq.q.ltoreq.3; d+f+p>0; p+q=3; R, R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are each
independently H, an alkyl radical having 1-20 carbon atoms, an aryl
radical having 6-20 carbon atoms, an alkylaryl radical having 1-20 carbon
atoms, an alkenyl radical having 1-20 carbon atoms, or halogenated
derivatives of the foregoing; wherein the organosilicate is present in an
amount sufficient to substantially inhibit ester-carbonate interchange in
the composition.
In the composition and method of this invention, the organosilicate
substantially deactivates the metallic catalyst residues so that the
residues lose their ability to catalyze a transesterification reaction
between the polycarbonate and the polyester.
DETAILED DESCRIPTION OF THE INVENTION
The term "metallic catalyst" and "metal catalyst" as used herein refers to
those metal compounds which are known to be useful as catalysts in the
preparation of polyesters. Examples of such catalysts include organic or
inorganic compounds of arsenic, cobalt, tin, antimony, zinc, titanium,
magnesium, calcium, manganese, gallium, sodium, lithium, and the like.
Titanium compounds are frequently used. Examples of these include the
tetraalkyl titanates, such as tetraisopropyl titanate and
tetra(2-ethylhexyl)titanate. Metallic catalysts useful in the preparation
of polyesters are described, for example, in U.S. Pat. No. 4,401,804
(Wooten et al.), which is hereby incorporated by reference herein.
Component A in the composition of this invention is at least one polyester.
The polyesters present in the composition and used in the method of this
invention are poly(alkylene dicarboxylates), which normally comprise
repeating units of the formula
##STR2##
wherein R.sup.10 is a saturated divalent aliphatic, alicyclic, or aryl
radical containing about 2 to about 10 carbon atoms and preferably about 2
to about 6 carbon atoms, and R.sup.11 is a divalent aliphatic, alicyclic,
or aryl radical containing about 2 to about 20 and preferably about 6 to
about 20 carbon atoms.
Examples of radicals represented by R.sup.10 include ethylene, propylene,
trimethylene, pentamethylene, hexamethylene, dimethylenecyclohexane,
tetramethylene, and 1,4-cyclohexylene. The straight-chain radicals are
preferred, especially ethylene, trimethylene, and tetramethylene, but
branched radicals are also contemplated.
The poly(alkylene dicarboxylate) used in this invention is preferably a
polyalkylene terephthalate or a polycyclohexylterephthalate. Preferably,
it is a polyalkylene terephthalate, and, most preferably, poly(ethylene
terephthalate) ("PET") or poly(butylene terephthalate) ("PBT"), with PBT
being more preferred than PET. It usually has a number average molecular
weight in the range of about 10,000-70,000, as determined by gel
permeation chromatography or by intrinsic viscosity at 30.degree. C. in a
mixture of 60% (by weight) phenol and 40% 1,1,2,2-tetrachloroethane.
The polyesters used in this invention are prepared by the reaction of at
least one alkenediol of the formula HO-R.sup.10 -OH with at least one
dicarboxylic acid of the formula HOOC-R.sup.11 -COOH or derivatives
thereof, such as, for example, dialkyl esters, diacid chlorides,
carboxylic acid salts, and diaryl esters. The dicarboxylic acid may be an
aliphatic acid such as succinic, glutaric, adipic, sebacic, azelaic,
suberic acid, or cyclohexane dicarboxylic acid; or an aromatic acid such
as isophthalic acid, terephthalic acid, naphthyl dicarboxylic acid, or
biphenyl dicarboxylic acid. The aromatic acids, especially terephthalic
acid, are preferred. The use of an ester and especially a lower alkyl
ester is preferred, the term "lower alkyl" denoting alkyl groups having up
to 7 carbon atoms, preferably, a methyl, ethyl, or butyl ester. The
reaction between the alkenediol and the dicarboxylic acid is typically
promoted by a metallic catalyst, examples of which were provided
previously herein.
Further suitable reagents for forming polyesters are described, for
example, in the following U.S. Patent Nos., all of which are hereby
incorporated by reference herein: 2,465,319; 2,720,502; 2,727,881;
2,822,348; 3,047,539.
For the preparation of the polyester, the dicarboxylic acid or ester
thereof, alkenediol and metallic catalyst are typically heated in the
range of about 180.degree.-300.degree. C. for a period of time sufficient
to produce the desired polyester. The mole ratio of diol to acid or ester
is typically from about 1:1 to about 1.4:1 and preferably from about 1.2:1
to about 1.3:1, the excess diol being useful to drive the reaction to
completion. The amount of metallic catalyst used is typically about
0.005-0.2 percent by weight, based on the amount of acid or ester.
For component B, the term "polycarbonate" as used herein embraces those
polycarbonates comprising repeating units of the formula
##STR3##
wherein Y is a divalent aromatic radical derived from a dihydroxyaromatic
compound of the formula HO-Y-OH. Typical dihydroxyaromatic compounds are
2,2-bis-(4-hydroxyphenyl)propane, also known as bisphenol A;
bis(4-hydroxyphenyl)methane; 2,2-bis(4-hydroxy-3-methylphenyl)propane;
4,4-bis(4-hydroxyphenyl)heptane;
2,2-(3,5,3',5'-tetrachloro-4,4'-dihydroxyphenyl)propane;
2,2-(3,5,3',5'-tetrabromo-4,4'-dihydroxyphenol)propane;
3,3'-dichloro-4,4'-dihydroxydiphenyl)methane;
2,2'-dimethyl-4-methylcyclohexyl bisphenol A; cyclododecyl bisphenol A;
cyclohexyl bisphenol, and 2,2'-dihydroxydiphenylsulfone, and
2,2'-dihydroxyldiphenylsulfide. Most preferably, Y is a
2,2-bis-(4-hydroxyphenyl)propyl radical, in which case, the polycarbonate
is a "bisphenol A polycarbonate".
Methods for preparing polycarbonates are known in the art and are
described, for example, in U.S. Pat. No. 4,452,933, which is hereby
incorporated by reference herein. Known processes for polycarbonate
preparation include melt processes and interfacial polymerization.
Polycarbonates can be prepared, for example, by reacting the
dihydroxyaromatic compound with a carbonate precursor such as phosgene, a
haloformate or a carbonate ester, a molecular weight regulator, an acid
acceptor and a catalyst.
Examples of suitable carbonate precursors include carbonyl bromide,
carbonyl chloride, and mixtures thereof; diphenyl carbonate; a
di(halophenyl)carbonate, e.g., di(trichlorophenyl) carbonate,
di(tribromophenyl) carbonate, and the like; di(alkylphenyl)carbonate,
e.g., di(tolyl)carbonate; di(naphthyl)carbonate;
di(chloronaphthyl)carbonate, or mixtures thereof; and bishaloformates of
dihydric phenols.
Examples of suitable molecular weight regulators include phenol,
cyclohexanol, methanol, alkylated phenols, such as octylphenol,
para-tertiary-butyl-phenol, and the like. The preferred molecular weight
regulator is phenol or an alkylated phenol.
The acid acceptor can be either an organic or an inorganic acid acceptor. A
suitable organic acid acceptor is a tertiary amine and includes such
materials as pyridine, triethylamine, dimethylaniline, tributylamine, and
the like. The inorganic acid acceptor can be either a hydroxide, a
carbonate, a bicarbonate, or a phosphate of an alkali or alkaline earth
metal.
The catalyst which can be used are those that typically aid the
polymerization of the monomer with phosgene. Suitable catalysts include
tertiary amines such as triethylamine, tripropylamine,
N,N-dimethylaniline, quanternary ammonium compounds such as, for example,
tetraethylammonium bromide, cetyl triethyl ammonium bromide,
tetra-n-heptylammonium iodide, tetra-n-propyl ammonium bromide,
tetramethyl ammonium chloride, tetra-methyl ammonium hydroxide,
tetra-n-butyl ammonium iodide, benzyltrimethyl ammonium chloride and
quaternary phosphonium compounds such as, for example, n-butyltriphenyl
phosphonium bromide and methyltriphenyl phosphonium bromide.
The polycarbonate may also be a copolyestercarbonate as described in U.S.
Pat. Nos. 3,169,121; 3,207,814; 4,194,038; 4,156,069; 4,430,484,
4,465,820, and 4,981,898, all of which are incorporated by reference
herein.
Copolyestercarbonates useful in this invention are available commercially.
They are typically obtained by the reaction of at least one
dihydroxyaromatic compound with a mixture of phosgene and at least one
dicarboxylic acid chloride, especially isophthaloyl chloride,
terephthaloyl chloride, or both.
The ratio of polyester to polycarbonate is not critical to the present
invention, and may be determined by the individual practitioner of this
invention. Typically, the weight ratio of polyester to polycarbonate will
range from about 99:1 to about 1:99, preferably from about 95:5 to about
5:95, and most preferably is about 50:50.
The organosilicates (C) used in this invention are linear monomeric
compounds of the general formula
(III) (R).sub.a (R.sup.1 O).sub.b Si
or linear polymeric compounds of the general formula
(IV) (R.sup.2).sub.c (R.sup.3 O).sub.d SiO- -(Si(R.sup.4).sub.e
(OR.sup.5).sub.f O).sub.h -(Si(R.sup.6).sub.j (R.sup.7).sub.k O).sub.l
!.sub.n Si(R.sup.8 O).sub.p (R.sup.9).sub.q
or cyclic compounds of the general formula
##STR4##
wherein 0.ltoreq.a.ltoreq.3; 1.ltoreq.b.ltoreq.4; a+b=4;
0.ltoreq.c.ltoreq.3; c+d=3; 0.ltoreq.e.ltoreq.2; 0.ltoreq.f.ltoreq.2;
e+f=2; 0.ltoreq.h.ltoreq.20; 0.ltoreq.j.ltoreq.2; 0.ltoreq.k.ltoreq.2;
j+k=2; 0.ltoreq.l.ltoreq.20; 0.ltoreq.n.ltoreq.100; 0.ltoreq.p.ltoreq.3;
0.ltoreq.q.ltoreq.3; d+f+p>0; p+q=3; R, R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are each
independently H, an alkyl radical having 1-20 carbon atoms, an aryl
radical having 6-20 carbon atoms, an alkylaryl radical having 1-20 carbon
atoms, an alkenyl radical having 1-20 carbon atoms, or halogenated
derivatives of the foregoing; wherein the organosilicate is present in an
amount sufficient to substantially inhibit ester-carbonate interchange in
the composition.
Examples of radicals which can be represented by R and R.sup.1 in formula
(III) above include alkyl radicals, e.g., methyl, ethyl, and hexyl
radicals; aryl radicals, e.g., phenyl, tolyl, resorcinyl, and cresyl
radicals; aralkyl radicals, e.g., 2-ethylhexyl radicals; or alkenyl
radicals; e.g., vinyl radicals. Preferably, R.sup.1 is methyl or ethyl,
and R is ethyl or phenyl.
Examples of preferred organosilicates which can be used in the composition
and method of this invention include, for example, Si(OCH.sub.3).sub.4,
Si(OCH.sub.2 CH.sub.3).sub.4, Si(OCH.sub.3).sub.2 (OCH.sub.2
CH.sub.3).sub.2, (CH.sub.3).sub.3 Si(OCH.sub.2 CH.sub.3)(OPh).sub.2,
(CH.sub.3)Si(OCH.sub.2 CH.sub.3).sub.3, (CH.sub.3).sub.2 Si(OCH.sub.2
CH.sub.3).sub.2, (CH.sub.3).sub.3 Si(OCH.sub.2 CH.sub.3), Si(OCH.sub.2
CH.sub.3).sub.3 H, Si(OPh).sub.4, poly(diethoxy)silicate; and
poly(diethoxy)silicate; wherein Ph is a phenyl radical.
Most preferably, the organosilicate used in this invention is Si(OPh).sub.4
or Si(OCH.sub.2 CH.sub.3).sub.4, wherein Ph is phenyl.
The organosilicates used in this invention can be prepared according to
processes known in the art. Reference is made, for example, to W. Noll,
"Chemistry and Technology of Silicones", 1968, Academic Press Inc., pp.
81-82, which is hereby incorporated by reference herein. These compounds
are typically prepared by reacting organosilanes with alcohols or
alkoxides where pyridine or tertiary amines are used as acid acceptors.
The compounds can also be prepared by reacting tetra(organooxy)silanes
with organometallic compounds, preferably Grignard compounds and organic
derivatives of the alkali metals can be used.
The composition of this invention may further comprise (D) an inorganic or
organic colorant, e.g., a dye or pigment. Examples of such colorants
include the Ultramarine pigments, e.g., Ultramarine Blue; Ultramarine
Violet; C.I. Pigment Red 187; and C.I. Pigment Red 187. It is to be
understood, however, that, although the organosilicates are advantageous
in compositions containing acid sensitive colorants, the organosilicates
can also be used in compositions containing non-acid sensitive organic and
inorganic colorants.
The polymeric composition of this invention may further contain (E) one or
more agents to improve the impact strength, i.e., an impact modifier.
So-called core-shell polymers built up from a rubber-like core on which one
or more shells have been grafted are preferably used. The core usually
consists substantially of an acrylate rubber or a butadiene rubber. One or
more shells have been grafted on the core. Usually these shells are built
up for the greater part from a vinylaromatic compound and/or a
vinylcyanide and/or an alkyl(meth)acrylate and/or (meth)acrylic acid. The
core and/or the shell(s) often comprise multi-functional compounds which
may act as a cross-linking agent and/or as a grafting agent. These
polymers are usually prepared in several stages.
Olefin-containing copolymers such as olefin acrylates and olefin diene
terpolymers can also be used as impact modifiers in the present
compositions. An example of an olefin acrylate copolymer impact modifier
is ethylene ethylacrylate copolymer available from Union Carbide as
DPD-6169. Other higher olefin monomers can be employed as copolymers with
alkyl acrylates, for example, propylene and n-butyl acrylate. The olefin
diene terpolymers are well known in the art and generally fall into the
EPDM (ethylene propylene diene) family of terpolymers. They are
commercially available such as, for example, EPSYN 704 from Copolymer
Rubber Company. They are more fully described in U.S. Pat. No. 4,559,388,
incorporated by reference herein.
Various rubber polymers and copolymers can also be employed as impact
modifiers. Examples of such rubbery polymers are polybutadiene,
polyisoprene, and various other polymers or copolymers having a rubbery
dienic monomer.
Styrene-containing polymers can also be used as impact modifiers. Examples
of such polymers are acrylonitrile-butadiene-styrene,
styrene-acrylonitrile, acrylonitrile-butadiene-alpha-methylstyrene,
styrene-butadiene, styrene butadiene styrene, diethylene butadiene
styrene, methacrylate-butadiene-styrene, high rubber graff ABS, and other
high impact styrene-containing polymers such as, for example, high impact
polystyrene. Other known impact modifiers include various elastomeric
materials such as organic silicone rubbers, elastomeric
fluorohydrocarbons, elastomeric polyesters, the random block
polysiloxane-polycarbonate copolymers, and the like. The preferred
organopolysiloxane-polycarbonate block copolymers are the
dimethylsiloxane-polycarbonate block copolymers.
The compositions of this invention may further contain (F) one or more
stabilizers to protect the polymers from degradation due to heat or
radiation by ultraviolet light. The term "stabilizers" as it relates to
component (F) does not include the organosilicates described earlier
herein. Satisfactory stabilizers for use as component (F) in the
compositions of this invention comprise phenols and their derivatives;
amines and their derivatives; compounds containing both hydroxyl and amine
groups; polymeric phenolic esters and salts of multivalent metals in which
the metal is in its lower state; and organophosphites including alkyl,
aryl, alkylarylphosphites, and polyphosphites.
Representative phenol derivatives useful as stabilizers include
3,5-di-tert-butyl-4-hydroxy hydrocinnamic triester with
1,3,5-tris-(2-hydroxy ethyl-s-triazine-2,4,6-(1H,3H,5H)trione;
4,4'-bis(2,6-ditertiary-butylphenyl);
1,3,5-trimethyl-2,4,6-tris(3,5-ditertiary-butyl-4-hydroxybenzyl)benzene
and 4,4'-butylidene-bis (6-tertiary-butyl-m-cresol). Mixtures of hindered
phenols with esters of thiodiproprionic acid, mercaptides and phosphite
esters are particularly useful. Additional stabilization to ultraviolet
light can be obtained by compounding with various UV absorbers such as
substituted benzophenones and/or benzotriazoles.
It is also within the scope of the invention to incorporate ingredients
such as glass, reinforcing fibers, plasticizers, mold release agents,
flame retardants, antioxidants, fillers such as clay, talc, and mica, and
the like into the polycarbonate-polyester composition.
The polymeric composition of this invention can be obtained according to
any conventional method of preparing polymer mixtures. The individual
constituents are preferably mixed collectively in the melt (compounded) in
an extruder. The extrudate (in strand form) which emanates from the
extruder is chopped to pellets. The pellets may, for example, be further
processed in an injection molding machine.
The present invention is also directed to a method for inhibiting the
ester-carbonate interchange in a polyester-polycarbonate composition
comprising components (A) and (B) described hereinabove, wherein the
method comprises contacting the polyester-polycarbonate composition with
(C) at least one organosilicate described hereinabove and present in an
amount effective to inhibit ester-carbonate interchange in the
composition, which are those amounts also provided hereinabove.
The following examples illustrate the present invention, but are not
intended to limit the scope of the claims in any manner whatsoever. All
parts are by weight unless otherwise specified.
EXPERIMENTAL
In the examples below, the following terms have the meanings set forth
below:
"PBT" - a poly(butylene terephthalate) having a number average molecular
weight, as determined by gel permeation chromatography, of about 50,000
and a melt viscosity of about 8500 poise at 250.degree. C. Commercially
available from General Electric Company under the designation VALOX.RTM.
315.
"PC" - a bisphenol A polycarbonate having a weight average molecular weight
of about 68,000 and a melt flow of about 9.5 grams per 10 minutes at
300.degree. C. Commercially available from General Electric Company under
the designation LEXAN.RTM. 145.
"T.sub.m " - crystalline melting point of a sample on the second scan of a
DSC procedure wherein the sample is heated from 40.degree. C. to
290.degree. C. at 20.degree. C. per minute, held for 15 minutes, cooled to
40.degree. C. at 80.degree. C. per minute, held for 10 minutes, and then
heated from 40.degree. C. to 290.degree. C. at 20.degree. C. per minute,
after which the Tm is recorded.
".DELTA.H.sub.m " - crystalline heat of melting of a sample on the second
scan of a DSC procedure wherein the sample is heated from 40.degree. C. to
290.degree. C. at 20.degree. C. per minute, held for 15 minutes, cooled to
40.degree. C. at 80.degree. C. per minute, held for 10 minutes, and then
heated from 40.degree. C. to 290.degree. C. at 20.degree. C. per minute,
after which the .DELTA.H.sub.m is recorded.
"KM653" - a methylmethacrylate butadiene styrene copolymer supplied by Rohm
and Haas.
"Blendex 338" - an acrylonitrile butadiene styrene copolymer supplied by GE
Specialty Chemicals.
"KM330" - a methylmethacrylate butylacrylate copolymer supplied by Rohm and
Haas.
"B56" - a methylmethacrylate butadiene styrene copolymer supplied by Kaneka
Corporation.
EXAMPLES 1-7 AND COMPARATIVE EXAMPLE A
Examples 1-7 illustrate the ability of alkyl and aryl silicates to
stabilize PC/PBT blends. Specifically, tetraethyl orthosilicate (Example
1), tetraphenyl orthosilicate (Example 2),
tetrakis(2-ethylhexyl)orthosilicate (Example 3),
tetrakis(2-methoxyethyl)orthosilicate (Example 4), poly(diethoxy)siloxane
(Example 5), phenyl triethoxysilane (Example 6), and
diphenyldiethoxysilane (Example 7) are shown to be effective by the
examples below. Comparative Example A illustrates the degree of
instability of a blend which does not contain a stabilizer.
In Examples 1-7, compositions were prepared by co-extrusing PC and PBT in a
vacuum-vented 30 mm WP twin screw operated at 480.degree. F. (zone 1);
480.degree. F. (zone 2); 480.degree. F. (zone 3); 480.degree. F. (zone 4);
480.degree. F. (zone 5); and 480.degree. F. (zone 6). The compositions
contained a PC/PBT weight ratio of 50:50. The silicate materials were
added to the compositions in the amounts indicated in Table I below.
In Comparative Example A, the procedure followed in Examples 1-7 was
repeated except that no stabilizing additive was added to the composition.
The degree of stability of a PC/PBT composition and, consequently, the
stabilizing ability of the stabilizer added, is indicated by the
crystalline melting point and the crystalline heat of fusion of the
compositions containing said additives.
The crystalline melting points and the crystalline heats of fusion are
presented in Table I.
TABLE I
______________________________________
Examples 1-7 and Comparative Example A:
Crystalline Melting Points and the Crystalline Heats of Fusion
Example Amount T.sub.m
.DELTA.H.sub.m
______________________________________
1 0.5 218 26
2 0.5 218 24
3 0.5 217 25
4 0.5 220 24
5 0.5 218 25
6 0.6 212 22
7 0.65 204 17
Comparative 191 8
Example A
______________________________________
The results of Examples 1-7 and Comparative Example A indicate that the
sample containing the preferred materials are substantially more melt
stable than the sample containing no stabilizer.
EXAMPLES 8-13 AND COMPARATIVE EXAMPLE B
Examples 8-13 illustrate the ability of alkyl and aryl silicates to
stabilize PC/PBT blends containing impact modifiers. Specifically,
tetrakis(2-ethylhexyl)orthosilicate (Example 8) in a blend containing
KM653, tetraphenyl orthosilicate (Example 9) in a blend containing Blendex
338, poly(diethoxy)siloxane (Example 10)in a blend containing KM653,
poly(diethoxy)siloxane (Example 11) in a blend containing Blendex 338,
poly(diethoxy)siloxane (Example 12) in a blend containing B56, are shown
to be effective. Comparative Example B illustrates the degree of
instability of a blend which does not contain a stabilizer.
In Examples 8-13, compositions were prepared by co-extruding PC and PBT in
a vacuum-vented 30 mm WP twin screw operated at 480.degree. F. (zone 1);
480.degree. F. (zone 2); 480.degree. F. (zone 3); 480.degree. F. (zone 4);
480.degree. F. (zone 5); and 480.degree. F. (zone 6). The compositions
contained a PC/PBT/modifer/antioxidant ratio of 46/39/14/0.6. The silicate
materials were added to the compositions in the amounts indicated in Table
II below.
In Comparative Example B, the modifier used was KM 653 and the procedure
followed in Examples 1-7 was repeated except that no stabilizing additive
was added to the composition.
The degree of stability of a PC/PBT/modifier/antioxidant composition and,
consequently, the stabilizing ability of the stabilizer added, is
indicated by the crystalline melting point and the crystalline heat of
fusion of the compositions containing said additives.
The crystalline melting points and the crystalline heats of fusion are
presented in Table II.
TABLE II
______________________________________
Examples 8-13 and Comparative Example B:
Crystalline Melting Points and the Crystalline Heats of Fusion
Example Amount T.sub.m .DELTA.H.sub.m
______________________________________
8 0.5 209 3
9 0.3 219 19
10 0.5 211 17
11 0.5 216 17
12 0.5 214 17
13 0.6 223 17
Comparative
-- Not Present
Not Present
Example B
______________________________________
The results of Examples 8-13 and Comparative Example B indicate that the
sample containing the preferred materials are substantially more melt
stable than the sample containing no stabilizer.
EXAMPLE 14 AND COMPARATIVE EXAMPLE C
Example 14 illustrates the ability of alkyl and aryl silicates to stabilize
PC/PBT/glass blends. Specifically, tetraphenyl orthosilicate (Example 14)
is shown to be effective. Comparative Example C illustrates the degree of
instability of a blend which does not contain a stabilizer.
In Example 14, compositions were prepared by co-extruding PC and PBT in a
vacuum-vented 30 mm WP twin screw operated at 480.degree. F. (zone 1);
480.degree. F. (zone 2); 480.degree. F. (zone 3); 480.degree. F. (zone 4);
480.degree. F. (zone 5); and 480.degree. F. (zone 6). The compositions
contained a PC/PBT/glass/antioxidant ratio of 22/46.25/30/1.55. The
tetraphenyl orthosilicate was added to the composition at 0.3 parts per
hundred (pph) parts by weight of the PC/PBT/glass/antioxidant.
In Comparative Example C, the procedure followed in Example 14 was repeated
except that no stabilizing additive was added to the composition.
The degree of stability of a PC/PBT/glass/antioxidant composition and,
consequently, the stabilizing ability of the stabilizer added, is
indicated by the crystalline melting point and the crystalline heat of
fusion of the compositions containing said additives.
The crystalline melting points and the crystalline heats of fusion are
presented in Table III.
TABLE III
______________________________________
Example 14 and Comparative Example C:
Crystalline Melting Points and the Crystalline Heats of Fusion
Example T.sub.m .DELTA.H.sub.m
______________________________________
14 209 16
Comparative Not Present
Not Present
Example C
______________________________________
The results of Example 14 and Comparative Example C indicate that the
sample containing the preferred material is substantially more melt stable
than the sample containing no stabilizer.
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